Yan Aoqing, Luo Yi, Tian Hao, Pan Helin, Cao Yu, Niu Bo, Zhang Yayun, Long Donghui
Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China.
Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China.
J Colloid Interface Sci. 2024 Jun;663:665-673. doi: 10.1016/j.jcis.2024.02.186. Epub 2024 Feb 28.
Aerogels with low density and high porosity are extremely attractive for high-performance insulation, but their brittleness, complicated fabrication, and poor mechanical properties greatly limit their practical applications. Herein, we report an ultrahigh-strength silicone aerogel with an armor-like epoxy framework via a temperature-controlled sequential reaction strategy. The key to this synthesis is forming a Si-O-Si framework via the polycondensation of silanes at 100 °C, followed by in-situ armoring an epoxy framework via an intermolecular cyclization at an elevated temperature of 150 °C. Owing to the enhanced framework, the resulting aerogel could withstand capillary tension in the drying process, enabling it to be dried at ambient pressure without shrinkage. The obtained aerogel possesses a tunable density of 0.17-0.45 g/cm and ultrahigh-strength with compressive modulus up to 37.8-244.3 MPa, which surpasses other polymer-reinforced silicone aerogels by a factor of five in mechanical properties. It also demonstrates outstanding thermal insulation, with an extremely low thermal conductivity from 0.025 to 0.051 W m K at room temperature, and maintains thermal characteristics across a temperature range of -20 to 300 °C. Furthermore, the aerogel composites prepared by the reinforcement of low-density fiber mats have tunable densities of 0.36-0.87 g/cm, much enhanced tensile strengths of 15.9-72.3 MPa, and low thermal conductivities at room temperature of 0.042-0.078 W m K. This study presents a cost-effective method for enhancing the production of silicone aerogel materials, offering considerable opportunities for their application in insulation, energy transport, and the aerospace sector.
低密度和高孔隙率的气凝胶对于高性能隔热极具吸引力，但其脆性、复杂的制备工艺以及较差的机械性能极大地限制了它们的实际应用。在此，我们通过温度控制的顺序反应策略报告了一种具有类似铠甲的环氧骨架的超高强度硅气凝胶。这种合成方法的关键在于在100℃下通过硅烷的缩聚形成Si-O-Si骨架，随后在150℃的高温下通过分子内环化原位包覆环氧骨架。由于骨架得到增强，所得气凝胶在干燥过程中能够承受毛细管张力，使其能够在常压下干燥而不收缩。所获得的气凝胶具有0.17 - 0.45 g/cm的可调密度和高达37.8 - 244.3 MPa的超高抗压强度，其机械性能比其他聚合物增强的硅气凝胶高出五倍。它还表现出出色的隔热性能，室温下热导率极低，为0.025至0.051 W m⁻¹ K⁻¹，并在-20至300℃的温度范围内保持热特性。此外，通过增强低密度纤维毡制备的气凝胶复合材料具有0.36 - 0.87 g/cm的可调密度、显著提高的15.9 - 72.3 MPa的拉伸强度以及室温下0.042 - 0.078 W m⁻¹ K⁻¹的低热导率。本研究提出了一种经济高效的方法来提高硅气凝胶材料的产量，为其在隔热、能量传输和航空航天领域的应用提供了大量机会。
